Radio receiver



F. CUTTING RADIO RECEIVER May 5, 3936.

Filed Feb. 3, 1936 INVENTOR. FULTON Cu BY ING ATTORNE Y.

Patented May 5, 1936 UNITED STATES PATENT OFFICE 12 Claims.

This invention relates to power supply apparatus for radio receivers and the like, and more particularly to improvements in the power supply apparatus by which alternating current may be drawn from a line and supplied to the cathodes, of either filament or heater type, of the various vacuum tubes employed .without change in its form, and also by means of which its form may be changed, as by rectifying it and filtering it to furnish direct current and direct current voltage for the various tubes electrodes.

In most radio receiving apparatus intended to operate with alternating current, it is customary to employ a transformer having separate primary and secondary windings, there generally being one secondary winding for supplying high voltage for rectifiers of current to be applied to the plates of the vacuum tubes used, and a separate secondary winding for each class of tubes having a differently rated filament. In commercial radio receivers of the present day type, there may be found as many as half a dozen different secondary windings on the transformer, these various windings furnishing current at diiferent voltages.

It is an object of the present invention to improve radio receiving apparatus by eliminating the physically separate multiple secondary windings and to provide a system in which a single winding may supply all of the desired currents and voltages.

Another object of my invention is to reduce the cost and size of the power transformer in the apparatus above mentioned, by providing a system in which the iron core and the size of wire ordinarily used in such transformers may be materially reduced in size, with consequent reduction in cost.

It is a further object of my invention to provide such a system, in which tubes having different ratings may be operated with the cathodes connected in series, without danger of overloading or underloading any tube.

It is a still further object of my invention to provide a radio receiving system in which the circuits have been simplied and reduced, making for quicker and easier assembly of the receiver in mass production.

It is an even further object of my invention to provide apparatus having the above mentioned advantages without introducing any new disadvantages.

Still other objects and advantages of my invention will be apparent from the specification.

The features of novelty which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention, itself however, both as to its fundamental principles and as to its particular embodiments, will best be understood by reference to the specification and accompanying drawing, in which Figure 1 is a simplifier diagrammatic circuit of one form of apparatus according to my invention;

Figs. 2, 3 and 4 are similar diagrams of other forms of my invention.

In the various figures of the drawing like reference numerals indicate like parts.

I represents any convenient source of alternating current such as is obtained by plugging into a Wall outlet. 2 is a transformer of the type known as an auto-transformer comprising a multiplicity of turns of wire, wound around a core, shown diagrammatically in the drawing, of magnetic material such as laminated iron.

In the arrangement shown in Fig. 1, the alternating current drawn from the source I is supplied to the transformer through conductors 6 and 1. Conductor 1 may be connected at one end terminal of the auto-transformer winding, and conductor 6 at an intermediate point, the opposite terminal of the auto-transformer winding being connected to the anode 4 of a rectifier tube 3 having a cathode 5 of the indirectly heated type. Since'the construction and operation of such rectifiers forms per se no part of my invention, and is well known in the art, it is not described in detail except to say that the tube 3 is shown as of the type in which the cathode 5 is indirectly heated and caused to emit electrons, and when so heated, the rectifier 3 passes current only during one-half of the cycle.

Connected from the cathode 5 to the con-- ductor 9 there may be a condenser Ill indicative of an arrangement for filtering out ripples and affording at the terminal marked a relatively smooth, non-fluctuating rectified voltage.

It will be understood that various other forms of filter systems may be employed, the same being well known in the art and forming per se no part of this invention.

In the radio receiver there may be provided a plurality of vacuum tubes of the diode and multiple electrode type indicated at H, which may be amplifiers, oscillators and detectors. These tubes are indicated as respectively having an indirectly heated cathode, or filament, l2, l3, I4 and I5, and these heaters are all connected in series. The complete series is connected between conductor 9 and a point on the winding of the auto-transformer 2 between the point of connection of conductors 1 and 9 and that of conductor 6, the number of turns in the auto-transformer winding and the points of connection of the conductors 6, 1, 8 and 9 being so chosen as to provide the desired voltages between the various points of connection. The heater of the rectifier may be connected in series with the cathode circuit of the tubes H. In the systems contemplated, a step-up ratio is provided to the rectifier 3 and a step-down ratio is provided to the various connections shown to supply the heaters.

Since the various tube and control circuits which may be utilized in the radio receiving apparatus form per se no part of this invention, the same are omitted for purposes of simplicity, it being understood that any desired circuit maybe used.

Referring again to Fig. 1, it will be observed that in operation of the auto-transformer, the winding connected between conductors 6 and. 1 serves as the primary of the transformer and part of the high voltage secondary. It will also be seen that apart of the same primary serves as the low voltage winding for supply filament current to the tubes.

This construction results in a cancellation of part of the primary and secondary currents flowing in the same winding, because of the reversed phase of such currents, which makes it possible to use much smaller wire than is used in the conventional transformer having multiple secondaries, and also permits the use of a smaller amount of iron in the core of the transformer with the net effect of a very considerable reduction in the size and weight of the transformer. In certain instances I have found that by so constructing the system, it is possible to reduce the cost of the transformer to one-half of that of the conventional design.

For most economical results, the step-up ratio from the primary to the high voltage secondary winding should be 1 to 2, and the step-down ratio to the filament winding 2 to 1. In such cases and for vacuum tubes of the type now customarily employed, it is sometimes preferable to connect the heaters of the said tubes in series, but the same is not in all cases necessary to secure the above referred to advantages, as the tubes may, if desired, be connected in parallel, or some of the tubes may be connected in parallel and the parallel connected tubes connected in series with other tubes.

If all of the tubes do not draw the same heater current, or if they tend to draw different currents during the period of heating, the arrangement of Fig. 2 may be utilized to advantage, in which the tubes are shown as having their cathodes connected in series, and the series connected tubes connected across the transformer secondary with intermediate taps l6 and I! connected to intermediate points on the secondary windings of the transformer as desired. With this ar-' rangement tubes having dissimilar filament or heating characteristics may be used in series without overloading or underloading any of them, a condition which it would be impossible to obtain if the intermediate connections l5 and H were not provided. Although the winding of the autotransformer is unitary, the turns included within the various taps constitute in effect separate secondaries so that the voltage across these taps is not substantially disturbed by the currents flowing in the various heaters. Additional intermediate connections between other tubes may be provided ifdesired, and any of these intermediate tap connections may be quickly and easily made as circumstances warrant without disturbing the remainder of the circuits of the radio receiver.

While I usually prefer to use a half-wave rectifier system as shown in Figs. 1 and 2, because this eliminates the use of a center tap and an extra winding and provides the highest voltage with a minimum amount of wire, nevertheless it is possible to use full wave rectifier systems which may be accomplished in the manner shown in Figs. 3 and 4, in which the transformer winding is extended as shown at 2 which winding is connected to a second half wave rectifier, so that the lead 1 instead of being connected at one end of the transformer winding, is connected at an intermediate point.

It will be noted that the cathode heaters are again shown as connected in series with the cathode heaters of the various vacuum tubes ll. While two separate half wave rectifier tubes have been illustrated, it will be understood that a single full wave rectifier tube of standard construction may be substituted in the circuit.

While I have shown and described certain embodiments of my invention, it will be understood that modifications and changes may be made without departing from the spirit and scope of my invention as will be understood by those skilled, in the art. I

Iv claim:

1. A power supply system for radio receiving apparatus and the like, comprising, in combination, connections adapted to be connected to a source of alternating current, an auto-transformer, said connections being connected to said auto-transformer across less than'the entire winding so as to provide a voltage step-up in said auto-transformer, means for rectifying the stepped-up voltage thereby produced, a plurality of vacuum tubes each having a cathode, connections from said auto-transformer across a lesser number of turns than the number included between said first named connections to provide a voltage less than the primary voltage for energizing the cathodes of the plurality of vacuum tubes.

2. A power supply system for radio receiving apparatus and the like, comprising, in combination, connections adapted to be connected to a source of alternating current, an auto-transformer, one of said connections being connected to one end of said auto-transformer, the other of said connections being connected to an intermediate point on said auto-transformer, a connection from the said end of said auto-transformer to the energizing circuit for the cathode of at least one vacuum tube. a return connection from said energizing circuit to a point on said auto-transformer intermediate the points of connection of the connection to'the alternating current supply, and a connection from the other end of said auto-transformer to a rectifier.

3. A power supply system for radio receiving apparatus and the like, comprising, in combination, connections adapted to be connected to a source of alternating current, an auto-transformer, said connections being connected to said auto-transformer in a manner to provide a secondary voltage higher than the primary voltage, a plurality of vacuum tubes each having a cathode energizing circuit, means connecting said energizing circuits in a series network, and a connection from each end of said series network to said auto-transformer.

4. A power supply system for radio receiving apparatus and the like, comprising, in combination, connections adapted to be connected to a.

source of alternating current, an auto-transformer, one of said connections being connected to one end of said auto-transformer, the other of said connections being connected to an intermediate point on said auto-transformer, a plurality of vacuum tubes each having a cathode energizing circuit, means connecting said energizing circuits in a series network, one end ofsaid series network being connected to the end of said autotransformer to which the first named connection is connected, and the other end of said series network being connected to a point on said autotransformer intermediate the points of connection of said first-named connections.

5. A power supply system for radio receivin apparatus and the like, comprising, in combination, a pair of connections adapted to be connected to a source of alternating current, a stepup auto-transformer connected to said connections, a rectifier connected to one end of said auto-transformer, a plurality of vacuum tubes each having a cathode energizing circuit, means connecting said energizing circuits in a series network across a portion of said auto-transformer, and at least one tap extending from a point intermediate the last mentioned connections to said auto-transformer to an intermediate point in said series network.

6. A power supply system for radio receivers and the like, comprising, in combination, connections adapted to be connected to a source of alterating current, an auto-transformer connected across said connections, a plurality of vacuum tubes having cathodes of difierent characteristics with each cathode having an energizing circuit,

means connecting said energizing circuits in a series network across a portion of said auto-transformer, and a connection from at least one intermediate point in said series network to a point on said auto-transformer intermediate the cathode supply points.

'7. A power supply system for radio receivers and the like, comprising, in combination, a pair of connections adapted to be connected to a source of alternating current, an auto-transformer, said connections being connected to intermediate points on said auto-transformer, rectifier elements connected to opposite ends of said auto-transformer, a plurality of vacuum tubes each having a cathode energizing circuit, means connecting said energizing circuits in a series network, said series network being connected to intermediate points on said auto-transformer.

8. A power supply system for radio receivers and the like, comprising, in combination, a pair of connections adapted to be connected to a source of alternating current, an auto-transformer, said connections being connectedto intermediate points on said auto-transformer, rectifiers connected to opposite ends of said auto-transformer, a plurality of vacuum tubes each having a cathode energizing circuit, means connecting said energizing circuits in a series network, said series network being connected to intermediate points on said auto-transformer, one of said intermediate points being the point to which one of the primary connections is connected.

9. A power supply system for radio receiving apparatus, comprising, in combination, a pair of connections adapted to be connected to a source of alternating current, an auto-transformer, a rectifier, a plurality of vacuum tubes each having a cathode energizing circuit, means connecting said energizing circuits in a series network, connections from said auto-transformer to said first named connections to said rectifier, and to said series network, the points of said connections being so chosen as to provide for substantial neutralization of current in a portion of said autotransformer.

10. A power supply system for radio receivers and the like comprising, in combination, connections adapted to be connected to a source of alternating current, an auto-transformer connected across said connections, a plurality of vacuum tubes having cathodes of diiTerent characteristics, and circuit connections for energizing said cathodes from points on said auto-transformer intermediate the alternating current connections.

11. A power supply system for radio receivers and the like, comprising, in combination, connections adapted to be connected to a source of alternating current, an auto-transformer connected across said connections, a plurality of vacuum tubes having cathodes of difierent characteristics, circuit connections for energizing cathodes of one characteristic in series across a portion of said auto-transformer, and circuit connections for energizing cathodes of different characteristic from other points on said autotransformer intermediate the alternating current connections.

12. A power supply system for radio receiving apparatus comprising, in combination, a pair of,-

connections adapted to be connected to a source of alternating current, an auto-transformer, a rectifier having a cathode and an anode, a connection from the auto-transformer to said anode, a plurality of vacuum tubes each having a cathode, energizing circuits for the cathodes of said rectifier and vacuum tubes connected in a series network, and connections from the series network to intermediate points on said transformer.

FULTON CUTTING. 

